NAME
    Imager::Bing::MapLayer - create a map layer for Bing Maps

VERSION
    Version v0.1.0

SYNOPSIS
        my $layer = Imager::Bing::MapLayer->new(
          base_dir           => $dir,     # base directory (default '.')
          overwrite          => 1,        # overwrite existing (default)
          autosave           => 1,        # save on exit (default)
          in_memory          => 0,        # keep tiles in memory (default false)
          min_level          => 1,        # min zoom level (default)
          max_level          => 19,       # max zoom level (default)
          combine            => 'darken', # tile composition method (default)
        );

        # Plot polygons (e.g. postcodes)

        $layer->polygon(
           points => $points,                  # listref to [ lat, lon ] points
           fill   => Imager::Fill->new( ... ), #
        );

        # Plot greyscale gradient circles for heatmaps

        $layer->radial_circle(
            r      => 100,              # radius in meters
            -min_r => 1,                # minimum pixel radius for any zoom level
            x      => $longitude,       # longitude (x = east-west)
            y      => $latitude,        # latitude  (y = north-south)
        );

        # Blur filter

        $layer->filter( type => 'gaussian', stddev => 1 );

        # Colourise greyscale heatmaps

        $layer->colourise();

DESCRIPTION
    This module is a wrapper around the Imager::Draw module, which allows
    you to create Bing map layers using longitude and latitude coordinates.

    The module will automatically map them to the appropriate points on tile
    files.

ATTRIBUTES
  `base_dir'
    The base directory to save tile files in.

  `in_memory'
    The timeout for how many seconds a tile is kept in memory.

    When a tile is timed out, it is saved to disk after each Imager drawing
    operation, and reloaded if it is later needed.

  `centroid_latitude'
    This is the default latitude for translating points to pixels. Generally
    you don't need to worry about this.

  `centroid_longitude'
    This is the default longitude for translating points to pixels.
    Generally you don't need to worry about this.

  `overwrite'
    When true (default), existing tiles will be overwritten rather than
    edited.

    Be wary of editing existing tiles, since antialiased lines and opaque
    fills will darken existing points rather than drawing over them.

  `autosave'
    When true (default), tiles will be automatically saved.

    Alternatively, you can use the save method.

  `combine'
    The tile combination method. It defaults to `darken'.

METHODS
  `levels'
      my @levels = @{ $layer->levels };

    This returns a reference to a list of Imager::Bing::MapLayer::Level
    objects.

  `min_level'
    The minimum zoom level to generate.

  `max_level'
    The maximum zoom level to generate.

  `radial_circle'
        $layer->radial_circle(
            r      => $radius_in_meters,
            -min_r => $min_radius_in_pixels,
            x      => $longitude,
            y      => $latitude,
        );

    This method plots "fuzzy" greyscale circles, which are intended to be
    used for heatmaps. The radius is scaled appropriately for each zoom
    level in the layer.

    If `-min_r' is specified, then a circle will always be drawn with that
    minimum radius: this ensures that lower zoom levels will always have a
    point plotted.

  `colourise'
        $layer->colourise();

    The method colourises greyscale layers. It is intended to be used for
    heatmaps generated using the radial_circle method.

  `filter'
        $layer->filter( type => 'gaussian', stddev => 1 );

    This applies Imager::Filters to every tile on every zoom level of the
    layer.

    Be aware that some filter effects may enhance the edges of tiles in each
    zoom level.

  `setpixel'
    Draw a pixel at a specific latitude and longitude coordinate.

    See the corresponding method in Imager::Draw for more information.

  `line'
    Draw a line between two coordinates.

    See the corresponding method in Imager::Draw for more information.

  `box'
    Draw a box bounded by northwest and southeast coordinates.

    See the corresponding method in Imager::Draw for more information.

  `polyline'
    Draw a polyline for a set of coordinates.

    Note that a polyline is not closed. To draw a closed area, use the
    polygon method.

    See the corresponding method in Imager::Draw for more information.

  `polygon'
    Draw a closed polygon for a set of coordinates.

    See the corresponding method in Imager::Draw for more information.

  `arc'
    Draw an arc.

    See the corresponding method in Imager::Draw for more information.

  `circle'
    Draw a circle.

    See the corresponding method in Imager::Draw for more information.

  `string'
    Draw a text string.

    TODO - the size is not scaled.

    See the corresponding method in Imager::Draw for more information.

  `align_string'
    Draw an aligned text string.

    TODO - the size is not scaled.

    See the corresponding method in Imager::Draw for more information.

  `save'
    Save the tiles.

KNOWN ISSUES
    For plotting very large polylines and polygones (e.g. postcode district
    `E17'), the system will die with no error message.

    See the TODO file for other known issues and unimplemented features.

SEE ALSO
        * Bing Maps Tile System

        http://msdn.microsoft.com/en-us/library/bb259689.aspx

AUTHOR
    Robert Rothenberg, `<rrwo at cpan.org>'

BUGS
    Please report any bugs or feature requests to the author, or through the
    web interface at https://github.com/robrwo/Imager-Bing-MapLayer/issues.

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc Imager::Bing::MapLayer

    You can also look for information at:

    * GitHub
        https://github.com/robrwo/Imager-Bing-MapLayer

ACKNOWLEDGEMENTS
    *   Foxtons, Ltd.

LICENSE AND COPYRIGHT
    Copyright 2013-2014 Robert Rothenberg.

    This program is released under the following license: atistic2